What we do.
We have cruised with our boys (ages 9 and 4), since they were both 1yr. For safety, the boys both wore harnesses until they were 4, and still do if the wind picks up. Of course they also wear life jackets while in the cockpit. Buy hats, lots of sunscreen, and keep the kids hydrated.I'm not sure this was a part of your question or not, but.....To keep kids happy while cruising we have learned the following lessons.1) It's all about the destination. The thrill of sailing may entertain you for hours, but kids become bored fast and they will soon start with "Are we there yet". Make the destination something exiting2) Keep trips under 2 or 3 hours, or make a stop to go swimming.3) Boat toys. For each child create a special bag of toys that they only play with on the boat. Occasionally put in a surprise.4) Give the older kids some responsibility. This gets easier as the kids get older, but even simple things like being on the lookout for other vessels helps them to feel like part of the crew.5) Play imagination games. We have sand spoils near our home harbor. We call them Pirate Island and make-up lots of pretend stories and games. We have even explored the island.6) Buy a 12V TV with VHS. Before you say we got the boat to get away from the TV, think about it, a 15min video will keep them happy while you dock the boat.Good luck and safe sailingPaul